JP2668554B2 - Shield construction method by cast-in-place concrete lining - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield method for excavating a tunnel or the like using a shield machine, wherein a lining is formed by cast-in-place concrete lining.

2. Description of the Related Art A conventional shield construction method involves injecting a backing material into a tail void (gap) created between a steel or concrete segment and a ground in parallel with the propulsion of a shield excavator, and then using a segment ring. It was a method of performing secondary lining with cast-in-place concrete on the inside.

However, recently, an inner formwork for lining concrete has been assembled in the shield tail at the rear of the shield machine, and concrete has been cast between the ground and the inner formwork. A shield construction method using cast-in-place concrete lining has been developed, which is characterized by forming a tunnel lining (for example, JP-A-56-13).
9398, JP-A-58-47900, JP-A-59-154299, JP-A-61-274098, JP-A-62-233399, etc.). The outer diameter of the inner form is equal to the finished inner diameter of the tunnel.

This new cast-in-place concrete lining shield method is
The drawbacks of this construction method are eliminated as follows.

(A) Since the lining can be constructed at once, the overall construction period can be shortened and the construction cost can be reduced.

(B) Since the tail void generated at the same time as the shield machine is propelled can be filled with the cast concrete, subsequent ground subsidence does not occur.

(C) Since concrete can be pressed under high pressure, a lining with high density and good water tightness is possible.

By the way, the shield method using the cast-in-place concrete lining is roughly classified into the following (I) and (I).
There is a type of I).

(I) The inner formwork (centre) is used, and the propulsion reaction force of the shield machine is obtained only for the inner formwork (JP-A-59-154299) or for both the inner formwork and hardened cast-in-place concrete. (JP-A-61-274098) Method.

(II) The segment as a structural skeleton is also used for the formwork,
The propulsion reaction of the shield machine is required only for the segment, or for both the segment and the hardened cast-in-place concrete.

The problem to be solved by the present invention The above-mentioned shield construction method using a new cast-in-place concrete lining has an advantage of solving the above-mentioned drawbacks of the conventional general, and is expected to be put to practical use in the future.

However, particularly in the case of using the above inner mold, there are the following problems.

(1) The inner formwork must be maintained until the cast concrete exhibits the desired strength. Therefore, an inner form is required over a section of a considerable length according to the shield excavation speed. Further, as the excavation speed increases, the length of the inner mold becomes longer, and the cost of the inner mold material increases.
That is, there is a problem that speeding up of construction does not necessarily lead to cost reduction.

(2) When the inner mold is diverted, it is necessary to perform operations such as cleaning and application of a release material after demolding. However, since the work space in the tunnel is generally small, it is difficult to perform the above-mentioned work, and it is difficult to reduce labor and labor costs.

(3) Propulsion reaction force is applied to the inner mold (Japanese Patent Laid-Open No. 59-
In the case of the method, the rigidity, strength and self-weight of the inner mold must be matched, and if this requirement is satisfied, the weight of the inner mold will inevitably increase. Therefore, as a method of quickly transporting the inner formwork to the predetermined position of the shield machine in order to convert the inner formwork to the next construction section, it is very difficult for humans to carry the equipment. Is required. As a result, not only does the speed of construction be adversely affected, but also there is a problem in ensuring the safety of workers.

(4) A method in which the propulsive reaction force of the shield machine is taken care of only by the set concrete (Japanese Patent Laid-Open No. 56-139398,
In the case of Japanese Unexamined Patent Publication No. 62-233399), the construction must be interrupted until the cast concrete has developed enough strength to withstand the propulsion force, so that the speed of the construction cannot be increased.

(5) In the case where the propulsion reaction force of the shield machine is given to the adhesive force between the inner formwork and concrete (Japanese Patent Application Laid-Open No. 61-274098), there is an adverse effect such as damaging the concrete at an early age. There is fear.

(6) The joint portion of the cast concrete becomes a cold joint, and water leakage easily occurs.

Next, if you want to use the segment as a formwork,
Since the strength and rigidity of the segments withstand the pressure of the cast concrete and the weight of the segments ensures the propulsion reaction of the shield machine, the segments are manufactured as large and heavy precast concrete plates with rebar. Therefore, in order to carry and assemble these segments one after another in accordance with the progress of the propulsion work, a transportation device such as a mobile erector is necessary, and there are various restrictions on increasing the construction speed, and there are various restrictions. Transporting and assembling the segments in the tunnel was troublesome, and there was a problem in ensuring the safety of workers.

Means for Solving the Problems As a means for solving the above-mentioned problems of the prior art, a shield method using a cast-in-place concrete lining according to the present invention is, as shown in the drawings, an example. In the above, for example, a discarded frame 2 made of fiber-reinforced high-strength precast concrete slab reinforced with aramid fiber, vinylon fiber, etc. is installed, and a support 3 for stiffening the discarded frame 2 from the inside is installed. 4 for placing concrete for lining by placing the concrete, and applying a propulsion reaction force to the fresh concrete 5 just cast via the end form 4 to propel the shield excavator 6. .

Action The scrap frame 2 is made thin and lightweight by a high-strength precast concrete slab mixed with aramid fiber or the like.

The pressure stiffness of the discarded formwork 2 is stiffened by the inner support 3, and withstands the concrete placing pressure and the pressure of the fresh concrete 5 bearing the propulsion reaction force of the shield machine 6.

The propulsion reaction force of the shield excavator 6 is transmitted as compressive force to the fresh concrete 5 cast into the inside thereof through the wife formwork 4, and inevitably the discarded formwork 2 and the support 3 for supporting the formwork 2 from the inside. The hardened lining concrete 1 and the ground 7 are also processed at the same time.

The fresh concrete 5, which bears the propulsion reaction force when the shield machine 6 is propelled, is strongly compressed to form a lining concrete with high density and good watertightness. At the same time as the propulsion of the shield machine 6, the tail void generated as a trace from which the tail portion 6a comes off is densely filled with the fresh concrete 5 compressed as described above to prevent the subsequent ground subsidence.

The support work 3 is immediately relocated to the next work area when the placed fresh concrete 5 develops a certain amount of strength.

Embodiment Next, the illustrated embodiment of the present invention will be described.

In the figure, 1 is a cast-in-place concrete lining that has already been constructed, 2 is a discard mold frame manufactured as a high-strength precast concrete slab, and 3 is a center that supports the inside of the discard mold frame 2 assembled to the tail part of the shield machine 6. Type (or jumping form type) support work.

The discarding frame 2 is manufactured as a fiber-reinforced high-strength precast plate reinforced by mixing, for example, aramid fiber or vinylon fiber or embedding it as a net-like reinforcing material. Since aramid fibers and vinylon fibers do not corrode, it is possible to manufacture thin-walled precast concrete slabs with small overburden. In addition, this high-strength precast concrete slab is dense and highly watertight, has a smooth surface, and has excellent chemical resistance and abrasion resistance, so that a highly durable concrete lining can be manufactured. Therefore, as an example, when the inner diameter of the tunnel is about 3000 mm and the thickness of the lining concrete 1 is about 400 mm, the thickness of the discarded formwork 2 is about 15 mm, and the weight of one divided six piece is about 60 kg, which is a thin and lightweight structure. ing. Since the scrap frame 2 is a precast product, the quality is also constant.

After assembling the reinforcing bar 8 inside the tail portion 6a of the shield machine 6, assembling the disposal frame 2 together with the tail portion 6 a and the existing hardened concrete (concrete lining 1) to form a concrete casting space, The inside of it is stiffened with the support 3 of the centle type. Further, the end face of the concrete casting space is closed by the end form 4 attached to the tip of the ram of the propelling jacks 9, 9 of the shield machine 6, and the concrete casting pipe 10 The concrete 5 pumped through the concrete pump is placed.

Immediately after placing the concrete 5, the shield jack 6 is propelled by the propelling jack 9. At this time, the propulsion jack 9 is moved to the fresh concrete 5 through the gable formwork 4.
To obtain a propulsion reaction force. During such promotion,
As a result of compressing the compressive force of the fresh concrete 5 and stiffening and supporting the formwork 2 with the support 3, the compressive force is transmitted to the hardened lining concrete 1 and the ground 7 for processing. 5 will be densely packed. Then, as a result of the propulsion of the shield machine 6, a part of the compressed fresh concrete 5 is press-filled at a high density into a tail void generated when the tail portion 6 a advances. Further, with the compression of the fresh concrete 5 and the filling of the tail void, the end form 4 pushed by the propulsion jack 9 slightly slips rearward, and as a result, the position of the joint of the lining concrete 1 is changed. The position of the seam of the scrap frame 2 is displaced to some extent. For this reason, a so-called splicing key in which the joints of the two are deviated from each other is formed, and the water stopping property is improved.

Advantageous Effects of the Present Invention As described above in connection with the embodiments, the shield method using the cast-in-place concrete lining according to the present invention has the following excellent effects.

Since the propulsion work of the shield machine 6 is started without waiting for the hardened concrete 5 to be cast, that is, in the state of fresh concrete, the construction is not interrupted, the construction is speeded up, and the construction period is shortened.

Since the propulsion reaction force of the shield machine 6 is obtained from the discarded formwork 2, the hardened lining concrete 1 and the ground 7 through the fresh concrete 5, the propulsion reaction force is applied only to the inner formwork or to the inner formwork. The lining concrete 1 can be formed with high quality without a risk of damaging or damaging the lining concrete 1 of a young age as compared with the conventional method required for both concrete.

Since the waste mold 2 is used and the inner mold is not used, there is no need to remove the inner mold, perform subsequent cleaning, apply a release material, etc., thereby saving labor and reducing labor costs. .

The discarded formwork 2 is manufactured as a thin, light-weight structure as a high-strength precast plate, which is advantageous for handling and transportation, and can reduce the size and simplification of a transport device such as a mobile erector. Safety can be improved.

The propulsion reaction force is applied to the fresh concrete 5 when the shield machine 6 is propelled to compress the fresh concrete 5, so that the concrete lining 1 having high density and excellent watertightness can be formed. At the same time, a part of fresh concrete 5 is filled into the tail void with high pressure,
The tunnel lining can be formed by placing the concrete once, and the man-hours can be saved.

Since the position of the wife formwork 4 that bears the propulsion reaction force of the shield machine 6 deviates from the joint position of the discarded formwork 2, the joint between the lining concrete 1 and the joint of the discarded formwork 2 is eventually displaced. A so-called piecing key is formed, and the waterproofness of the lining is greatly improved.

Since aramid fiber and vinylon fiber do not corrode, it is possible to produce a thin precast concrete slab with a small covering, and this high-strength precast concrete slab is dense, highly watertight, has a smooth surface, and is chemically resistant. Since it is excellent in heat resistance and abrasion resistance, it is possible to produce a concrete lining with high durability and is suitable for sewerage or the like through which various mixed materials (miscellaneous drainage) flow.

High-strength precast concrete slab for scrapping form 2
Is very cheap, so it is sufficiently economical even compared to the conventional construction method using an inner formwork.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a construction state of a shield machine for implementing the construction method of the present invention. 1 ... lining concrete 2 ... disposable formwork 3 ... support shoring 4 ... wife formwork 5 ... fresh concrete 6 ... shield excavator 7 ... ground mountain

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeshi Nagayama 8-21-1, Ginza, Chuo-ku, Tokyo Co., Ltd. Takenaka Civil Engineering Co., Ltd. (72) Inventor Yasuhiko Yoshioka 2-5-114 Minamisuna, Koto-ku, Tokyo Co., Ltd. Inside Takenaka Corporation Technical Research Institute (72) Inventor Toshio Yonezawa 2-5-14 Minamisuna, Koto-ku, Tokyo Inside Takenaka Corporation Technical Research Institute (72) Inventor Akio Suzuki 2-5-1-14 Minamisuna, Koto-ku, Tokyo Inside Takenaka Corporation Technical Research Institute (72) Inventor Katsunori Asai 2-5-1-14 Minamisuna, Koto-ku, Tokyo Inside Takenaka Corporation Technical Research Center

Claims (1)

(57) [Claims] (1) In a shield method using a cast-in-place concrete lining, a cast-off frame made of a high-strength precast concrete slab is installed, a supporter for stiffening the cast-out frame from the inside is installed, and a wife-form is installed. A step of casting concrete for lining, and taking a propulsion reaction force through the wife form to the freshly cast fresh concrete and propelling a shield excavator, a shield construction method using a cast-in-place lining. .